path: root/arch
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authorArnd Bergmann <arnd@arndb.de>2017-07-19 14:53:02 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-02 07:06:52 +0200
commit218720fe593965cb2bb45c3e463bb9991ceca40c (patch)
tree8ffaa3c94f951b3a683708b4904e678f3a89649b /arch
parenta7a074f3a4d547a525748bfde179c4eb787d4f47 (diff)
x86/io: Add "memory" clobber to insb/insw/insl/outsb/outsw/outsl
commit 7206f9bf108eb9513d170c73f151367a1bdf3dbf upstream. The x86 version of insb/insw/insl uses an inline assembly that does not have the target buffer listed as an output. This can confuse the compiler, leading it to think that a subsequent access of the buffer is uninitialized: drivers/net/wireless/wl3501_cs.c: In function ‘wl3501_mgmt_scan_confirm’: drivers/net/wireless/wl3501_cs.c:665:9: error: ‘sig.status’ is used uninitialized in this function [-Werror=uninitialized] drivers/net/wireless/wl3501_cs.c:668:12: error: ‘sig.cap_info’ may be used uninitialized in this function [-Werror=maybe-uninitialized] drivers/net/sb1000.c: In function 'sb1000_rx': drivers/net/sb1000.c:775:9: error: 'st[0]' is used uninitialized in this function [-Werror=uninitialized] drivers/net/sb1000.c:776:10: error: 'st[1]' may be used uninitialized in this function [-Werror=maybe-uninitialized] drivers/net/sb1000.c:784:11: error: 'st[1]' may be used uninitialized in this function [-Werror=maybe-uninitialized] I tried to mark the exact input buffer as an output here, but couldn't figure it out. As suggested by Linus, marking all memory as clobbered however is good enough too. For the outs operations, I also add the memory clobber, to force the input to be written to local variables. This is probably already guaranteed by the "asm volatile", but it can't hurt to do this for symmetry. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Borislav Petkov <bp@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tom Lendacky <thomas.lendacky@amd.com> Link: http://lkml.kernel.org/r/20170719125310.2487451-5-arnd@arndb.de Link: https://lkml.org/lkml/2017/7/12/605 Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index de25aad07853..9016b4b70375 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -304,13 +304,13 @@ static inline unsigned type in##bwl##_p(int port) \
static inline void outs##bwl(int port, const void *addr, unsigned long count) \
{ \
asm volatile("rep; outs" #bwl \
- : "+S"(addr), "+c"(count) : "d"(port)); \
+ : "+S"(addr), "+c"(count) : "d"(port) : "memory"); \
} \
static inline void ins##bwl(int port, void *addr, unsigned long count) \
{ \
asm volatile("rep; ins" #bwl \
- : "+D"(addr), "+c"(count) : "d"(port)); \
+ : "+D"(addr), "+c"(count) : "d"(port) : "memory"); \
BUILDIO(b, b, char)